This invention relates generally to sensing conditions in an exterior annulus between a casing, liner, or other tubular structure and the wall of the borehole of a well. It relates more particularly to sensing, such as with optical fiber technology, one or more parameters in such exterior annulus at least during a cementing treatment.
Service companies in the oil and gas industry strive to improve the services they provide in drilling, completing, and producing oil and gas wells. Cementing is a well-known type of service performed by these companies, and it entails the designing, producing, and using of specialized fluids. Typically, such a fluid is pumped into a well so that the fluid flows into the exterior annulus between a tubular structure, typically a casing or a liner, and the wall of the borehole. It would be helpful in obtaining, maintaining, and monitoring these fluids and flows to know downhole conditions as these fluids are being placed in wells, and especially in the exterior annulus of a well where data has not heretofore been readily obtained directly. Thus, there is a need for sensing these conditions and obtaining data representing these conditions from inside the exterior annulus at least as the fluids are being placed (that is, in real time with the treatment processes); however, post-treatment or continuing sensing is also desirable (such as for trying to determine progress of setting or hardening, for example). Such need might include or lead to, for example, monitoring pressure, temperature, and other parameters inside the exterior annulus and within the flow of cement or other fluid itself, monitoring cement setting and hardening times, estimating cementing job quality, improving treatment models, and enhancing correlation between actual cement setting times and laboratory-based results.